feat: add polished boot screen on CLI startup (#118)

* feat: add polished boot screen on CLI startup

Replace the minimal one-liner REPL banner with an ANSI-styled status
panel that summarizes the agent's runtime state after initialization:
model, database, tool count, enabled features, active channels, and
the gateway URL. The boot screen is shown only in interactive CLI mode
(skipped for single-message -m mode).

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR review feedback on boot screen

- Stop logging gateway auth token in tracing::info! (security)
- Use info.agent_name instead of hardcoded "IronClaw" in header
- Display embeddings provider in features line: "embeddings (openai)"
- Add Display impl for DatabaseBackend, simplify main.rs match

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

src/lib.rs

@@ -39,6 +39,7 @@
 //! - **Continuous learning** - Improve estimates from historical data
 
 pub mod agent;
+pub mod boot_screen;
 pub mod bootstrap;
 pub mod channels;
 pub mod cli;